Pile-driving apparatus



July l, 1930. J. H. THORNLEY vPILE DRIVING APPARATUS Filed A115 15 1925 2 Sheets-Sheet 1 l DJM I July 1, 1930. J. H. THORNLEY PILE DRIVING APPARATUS 2 shams-sheet 2 Filed Avg. 15 192s Nv. f4

Numa

m um l 5 III Meg 42 laan,

Patented July 1,1930

weg.

Finn-newme- Arrirnnrus Application filed August 13, 1926. VSerial No. 128,939. v

rlhe present invention relates to pile driving apparatus, and has particular reference to improvements devised 'to enable the upper ends of piles to be driven below ground level, y'lhis is impossible with the ordinary pile driving hammer. rlhc guides or leads of the derricl: can 'only extend tok thev ground level, and obviously the hammer unit cannot continue with the movement of the piledown below the ends of the leads and into the ground. p n

The desirability of driving piles below ground' level is frequently encountered in construction'worlr', and' heretofore this practice has involved considerable expense or has been otherwise objectionable. 'A typical situation wherein it isdesire'd to'drive piles below ground. level is illustrated in the' case'of a base, column or pedestal which Vis to beset down in a pit in the surface of the ground and which is to be supported on the upper ends ofpiles driven into the ground. Heretofore, in erecting` this type of foundation, Vhe piles are first driven down as far; as pos. sible with the ordinary'pile driving hammer',l

wiich in practically all cases leaves some' portion of the pile-end projecting above-the ground level. rlhereafter, ay pit is dug'dowii to the desired depth byldigging the earth from around and between, the piles.y Finally,

the upper ends of the piles are cut ofin at the" proper point to leave their remaining ends' projecting to the desired distance above the bottom of the pit. The difficulty of eircavatl ing around and between the closely grouped piles, and the difficulty of sawing oif the upper portions ofthe piles at the bottom ofthe excavation makes the labor costy on this method very high. Furthermore, the'load'bearing value of that portion of the pile which is cut .off -is lost, and there is considerableloss of timber in the out o ends.

ln attempting` to circumvent these difficul-- ties, it has been proposedA to use ordinary loose followers interposed between the rain of the hammer and the head of thepile for the principal objections has .been the inability to guide the follower properly. The guiding of the upper end of the `follower is notv such a problem,but -`the difficulty arisesin guiding the lower' end of the follower-and therefore the'upper endof the pile`-in driving the pile below ground level. lfthe pile is the least bit out of linev with the guides of the derrick, the upper end of the pile will tend to lriclr sidewise under the blows transmitted through the follower. rlliefreedom 'of the lower end of the follower to kick sidelwise at such times also aggravates this objectionable tendency of the pile head tofliclrorspring side'wise. The net result of such lateral springing' or kicking of the pi'lelfis that the earth bond around the upper portion of the` kpile is loosened and greatly diminished in strength so that the load bearing value ofthe entirey pile is lessened. l

`i/liiio'ther ob'jectiont'o the useof such follower' liesin the inability to judgeaccurately the load bearing value' of the pile after it" has .beeii driven t'o approximately its' desired' depth. lt is customary, particularly incertain soils, to testfthe loadbearing vvalue of the( pile as it approaches the bottom of itsv penetration by measuring the depthfof penetration resulting from'eachy blow of the ham` mer.. lhen the ordinary loose follower is employed this' method of ,determinirig'load bearing; value is deprived of all' certainty. Such a follower is frequently of larger 'dii-f ameter than the pile,and the frictional resistance thereof with the soil is generallyaof such degreev that it is impossible tot'ellwhat proportion' of the resistance opposed' to the drivingfa'ction of the hammer represents-the loadbearing value of the pile and what proa portionrepresents the load bearing` value of the follower.r Thus, after lifting the follower from the head'of the pile, the pile remains with an indeterminate load bearing` value.

y Another objection to the use of' such followers arises 'from the spring or resiliency therein. Such followers are vgenerally, constructed of ya sectionof timber six or eight. feetY long', and the" spring in this lengthof timber isoften sufiicient to lessen the inten-` sity' of the blow delivered to the pile. rlhe net'result ofy all of these objections has been that in many localities throughout the coun'- try the building codes now expresslyv prohibit the dri-ving of piles with a follower, particularly where the piles are required to have a definite load bearing value. As before stated, the need of driving piles below ground level is frequently encountered in construction work to facilitate the building of foundations etc., and where these piles must have their definite load bearing value, or when they are driven in a locality where the use `of a follower is prohibited, it is still necessary -to pursue the expensive practice of driving the piles down approximately to ground level and thereafter excavating around the piles and then cutting oil the upper portions of the piles. Y

It is the fundamental obj ect of the present invention to provide improved means for drivingpiles below ground level which will avoid these prior objections and which vill enable piles to be driven in a manner coinplying with the requirements of the building codes. More speciiically, it is an object of the invention to provide an improved construction of pile driving hammer characterized by an extended base and contained core for driving the piles. p

A further object of the invention is to provide a construction wherein the penetration of the pile'for each blow of the hammer during the latter part of the driving of the pile can be measured accurately and without being subjectto the opposing pressures of the base extension, It is a further object to provide apparatus of this type which will serve to drive composite piles having metallic sleeve extensions on their upper ends. These piles are generally constructed of a section of wood piling, to Vthe upper endfof which ametallic sleeve is either bolted or spiked with'the upper end of the sleeve project-ing considerably above the top of the woodpile. Such piles are Lusually driven. to bring the top ofthe slee-ve extension to a desired level, either above or below ground level, and thereafter the hollow interior of the lextended sleeve portion is filled with concrete to support a cap, pedestal, base or other foundation member. In driving such piles it is practically imperative that the driving blows be imparted directly to the upper end of the wood pile as distinguished from the sleeve. One einbodiment of my improved apparatus has been designed to drive piles of this type, and in such embodiment the central core or impacting member is arranged to operate within the sleeve extension for applying the driving blows directly to the upper end of the wood ile.

A further object of the invention is to einbody this -apparatus in a detachable unit which. may be readily mounted upon or dismounted from a standard assembly of pile driving hammer so that the unit can be quickto Vdrive ly applied andv removed in adapting the haininer to different classes of work.

Other objects and advantages will be apparent from the following description of a preferred embodiment of my invention.

In the drawings illustrating this embodiment: Y

Figure 1 is a front elevational view illus- J l t) n n s tracing a standard hammer unit with my iinproved base extension mounted thereon, the

apparatus being shown supported between the guides of the derrick and in the act of driving a pile.

Fig. 2 is a vertical sectional view through the base extension and core illustrating the mounting of this base extension on the base of the hammer unit.

Fig. 3 is a similar sectional view illustrating the relation of the base extension and core in the act of driving a pile below ground level.

Fig. 4 is a transverse sectional view taken on the plane of the line 4 4 of Fig. 2.

F ig. 5 is a perspective view of one of the brackets for connecting' the base extension to the standard base member.

Fig. 6 is a perspective view illustrating the upper end of the base extension with the several supporting brackets riveted thereto.

Fig. 7 is a perspective view of one of the releasablc coupling keys which serve to couple the casing and core of the base extension7 and Fig-.8 is a verticalsectional view of another embodiment of t-he invention designed y .the composite piles before mentioned. 'Y

Referring to Figure 1, the two vertical guides or leads of the pile driving derrick are indicated' at 11-11. Sliding between these guides is a hammer unit 12, whicli,'for the greater part, is of any standard construction of either single or double acting type. Generally, these units comprise an upper steam cylinder 13, a lower base member 14 and an intermediate reciprocating ram 15. The ram connects to a piston rod 16 entering the bottom of the cylinder 13 and being attached to a piston reciprocating in this cylinder. Any suitable valve mechanism 17 serves toadmit and discharge the steam from the cylinder.

The unit is guided by two guide channels 18-18 extending substantially from end to end thereof and engaging over the rails or flanges of the leads 11. The base member 14 is connected to the cylinder 13 by columns 1 generally four in number, which are keyed at their upper ends in a flange formed on the lower end of the cylinder 13 and which at their lower ends enter sockets 21 formed in the top of the base member 14, in which sockets they are similarly secured by remov-v Lives-116e en -ee,Ofthe cylinder 13m the movement-of the vcylinder betweenthe-leadslla gages within the opening 24. vThe preceding construction of hammer has been chosen for illustrating the present invention: merely because it represents a popular, conventional type, but itwillbe understood that the in- Y vention has application vto other types ofh'ammer'units as well.

u Inembodying my improvements in this typeiof hammer unit I employ a Vbase eXtension, indicatedk in its entirety at 25, which depends lfrom the main base member 14.

This base extension functions as a guide for arcontained core orimpactingfmember27 and forfthe headend of the pile 28; To this end, itmay be constructed in various forms, the

principal requirement beingthatit havey ample guiding and bracingrigidityfor guiding the core 27 andpile 28'. v For simplicity of construction I preferably make the same from a section-of heavy pipe or tubing 26, cut; -to thel desired length. F or most purposes this length will beapproximately six or eight Y feet, but it may be extended to muclrgreater lengths for. deep driving, if desired. The upper end of the casing 26is `firmly anchoredy to the base member 14l by .a plurality of heavy brackets 29iwhich, areriveted: to; the sides of thefcasing and which embrace andare connectedto the base member.

One of such brackets isshown in'Figure 4,

from which'it will be,seen-that it consistsof a sectionof l-l'beam` having its flanges and'. web cut away to form the necessary attaching surfaces. v The inner flange 31 is provided with'v a .plurality of` rivet holes 32 by which` .Y thisflangeof the bracket isrivetedtothe upper end of the casing 26. This-flange may befbowledi or curvedon avlongitudinal axis toaiford maximum` area of contact with the side wall of the casing. .The-upperend' of the outer flange 33 is folded'inwardlyy t'o form a hook likesupporting Amember 34 for engagu ing over the top of the basememberj Thel web` 35 is cut back intermediate the" top of the inner flange 31-and the outer. flange 33,

- thisfcut away portion receiving the side surfaces of the base member 14. There arepreferably fourofsuch brackets spacedV equidistantly aroundl the casing 26,y as best shown in Figure 6, andtthesefbrackets embrace the sides or corners of the base member.. When.

fastened to the core member. functions as an upper guide surfaceffor guid-4 they casing'is being ydriven intoth'e: groundV in the. operation of driving the pile,fthe.en. tire upper end thereof Ybears against the flat bottom of the base member14thereby affordf ing an extensive area. of bearin'gsengagement. e

between the base. andbase extension for retaining the two in alinemenu The shoulders 3G, formed by the Vupper ends of the bracket flanges 3l and by th'ecut away portionsofk the webs 35, also increase this area of bearing engagement. lVhen the casing is .being with* drawn .from the ground after; the pile' has been completelyvdriven, 'the-effortof lifting theV casing by the h ammerunit is imposedgon the hook like extensions 34. This-withdrawing. effort is much less thanthe drivingy effort of the cas-ing. rlhese hook like extensions have holes 37 therein through'which pass vthe lower ends of the columns 19 in effecting their anchored engagement kin the base 14, and this engagement of the members 34e with-.the

columns prevents any possibility of the base extensionbecoming accidentally disengaged from the hammer unit.; '.Nhenit is desired to adapt the hammer. umttoother classes of: work the entire base assembly consistingof the main base memberl 14,-l and. thebase extene` sion 25 may be removed` for su'bstitutionby a, standard base member' (similar-,to thebase member 14) by simply removing-the? keys22 or, the entire base assembly can be rst removed in this manner, and thereazfgte'r'th'e main basemember-14 canbedi'sengagedfrom the base extension 25-and= replacedy on; the supporting columns 19.- rlhe'keys 22 can bel removed by simplydriving; themfrom one endk out'of their sockets int-thefbasemember 14. Y

Containedwithin the casing 26 fis acore-on impacting member 27, preferably constructedofy metal, such Ias* steel. The lower endrjof.r this member is preferably formed with an enlarged head 41 in which is formediav tapered socket 42 for receivingthe upper end =of the pile 28. n Itywill bequnderstood that the-:pile 28 is representativeeither cf'a woodpile, ay precast concrete pile, a steel pile, or any. other type ofV pile.l The lowenheadnof: thiscere member is guided within the lower portionfoff the-casing 26 either byjcontacting'witlrthe casing directly or through #bearing ring l4-3-l recessed in the periphery 'of the head portion. The upper end of the core member is tapered as indicated at 44 to be receivedwithin thev opening24in the base member. vThe drivmg blows of the ram extensionrlare nn:-

parted directly to this-tapered end of't'he core, the lower end of .the core normally: v resting on the heady end of the pile, and the4 velocity impact occurring between thev upL per endV ofthe core and the ram. DirectlyA `lbelow this tapered upperend'44f,`a relatively! wide collar 45 is keyed or otherwise rigidly This lcollarv ing the upperend of the core within the cas-Y rently with the driving ot the pile to make the casing follow the pile into the ground; This is the function of the keys 46. One ofV such f keys is shown in Fig. 7, from which it will be seen that it is constructed in the 'form oi an arcuate plate having a. downwardly turned lip 47 along its outer edge. rlwo of these keys are disposed at diametrically opposite sides of the casing, sliding in arcuate slots 48 cutin the sides of the casing and serving as key sockets or key ways. The inner edges of these keys are adapted to engage under the lower edge of the collar 45 while the core and casing are being driven together, the keys being held in this position by cap screws orv studs 49 which` engage in holes in the lips 47 of the keys and in the sides of the casing. The inner flanges 31 of the brackets 29 may be cut away at 5l in forming the slots 48, if the use of relatively wide keys is desired. The fastening of the brackets to the lcolumns 19 groupsthese brackets about the base 14so that one pair of brackets will lie on the outer side of the plane of the der-l rick leads, and the other pair on theinner side thereof where they will notinterfere with the leads. The two keys46-46 are similarly disposed on the outer and inner sides of the casing where they can be readily removed without interference by the leads.

A relatively long'vertical slot 52 is cut in the casing 26, extending above'andbelow the plane of the collar 45, through which the movement of the collar can be observed for reckoning the descent of the pile, and thereby determining the final load bearing value of the pile, after the keys 46 have been removed. 'y

In the operation of the apparatus, the base extension is centered over the upper end of the pile with the pile guided between the' leads 11, and thereupon `the pile is driven down into the ground approximately to the desired depth. When the pile is first started into the ground, and before the lower edge of the base extension 26 has engaged the ground, said base extension is free to drop .downwardly, the connected parts of the `hammer unit consisting of the cylinder 13 and base 14 of course moving downwardly with the base extension. be limited by the flaring recess 24 in the base member 14 engaging with the tapered end 44 of-thevcore, or by the lower'edge of the re- This downward movementA willV cess 24 striking the collar 45 on the core. After the driving operation has been f con# tinued tothe pointl where the base extension or casing 26 entersthe' ground, as shown in Fig. 3, a resistance is setup to further downward movement `ot the casing, and thereupon the'engagement of the collar 45 againstthe keys 46 compels the casing to-fol-low the pile clown into the ground.y Preparatory to delivering the last blow or blows to the pile, the keys 46 are withdrawn or released which disconnects the core 27 of the base extension from ythe casing thereof. Thereafter, the final blow or blows delivered to the core -will be only eective on the pile 28, and by sighting through the slotted 'opening 52, and watching the movement of the collar 45, the descent of the pile for each Vof such Vblows can be measured. This will give an accurate indication ofthe load bearing value of the pile, as the downward movement of the pile at this time is not impededv by the -resistance of the base extension. After these final blows,

the base extension and core are pulled up out of the ground through the'action of the hoistingr cables raising the hammer Y unit, where the core and casing are again'properly associated for the driving of another pile by the replacement of the keys' 46 in position below the collar 45. In order that the core and casing will not become separated during this withdrawing operatioma ring -0 is iXedly secured within the casing just below the slotv52. This ring or collarwill engagethe bottom of the collar on the core and hold the core within the casing during the operation of lifting the latter. i

lVhile the pile isbeing driven,"the upper end of the coref27 is held accurately centeredv 1n. the opening 24 of the base member, and any `lateral stresses set up between the upper end oftheV core and -thebase member, Y

incident inthe pile being deflected out of alinement with the leads, will be transmitted directly to the base member and thence to the leads. Hence, there is'no possibility ofv displacement of the upper end of the core or of the hammer unit from any such side thrust. Similarly, any lateral stresses set up between the pile head and the lowerV end of the core, arising from disalinement or deflection of the pile, will be resisted by the guiding `influence of the heavyvouter casing 26. The rigidity of the bearing engagement between this casingvand the basemember 14 will result in such lateral stresses being transmitted directly to the base member where they Ywillv of line, where the eilect of its blows wouldV be largely dissipated in flexing the upper pile and loosening the earthy portion of the bond thereof.

v The modification illustrated" in Fig.v 48 diders from the preceding embodiment principally in the provision of an annular space between the core and casing into which the' sleeve like extension on the upper end of the compesite pile can extend. -Thisfsleeve likeextension is indicated at 53, and consists of a very light shell, since its only function is to serve as ya temporary form for the concrete which is ksubsequently oined to the top of the wood pile. The lowere'nd of such sleeve extension is spiked or bolted to the upper end ofthe pileat 54; 'Thelower end of the core 27" is of sufficiently small diameter to pass down within this sleeve extension and engagethe upper end of tliefw'ood pile section directly. lf desired, the lower end of this lcore may be formed with a tapered socket 22" for engaging over the tapered upperv end of the wood pile. TheV inner diameter kof the casing 26 ina'yhave guiding contact at yits lower yend directlyl with the exterior of the sleeve 53, or a'rin'g 55 may be secured in the lower end 4of the casing for guiding contact with thesleeve. A relatively wide ring 56 is n preferably riveted or bolted to the interior of the casing l26 adjacent its upper end for guiding engagement with the upper portion l ofthe core. VThis guide ring affords a longi'.n tudinally extended bearing engagement between the core and i easing and avoids the necessity of be'aringcontact between the lower end yof the casing and the pile sleeve 53, .where this isA desirable. Such guide ring also holds has been driven to the point where theupper end of the sleeve 53 is at approximately the desired distance either above or below ground level, the baseextension andcore are removed. The load bearing value of the pile may, vof

course, be determined by removingthe keys 46 preparatory to delivering the last ,blow

i or blows. With the core and casing of thek extended ybase removed, the interior of the sleeve extension 53 may be `filled with con-v crete, and any suitable reinforcement eme. bedded therein, for mounting an upper cap, pedestal or the like.

4 It willbe observed that by driving ,the piles according to this methodv any pit yor excava-y tion which'may be desirable Afor receiving such cap, pedestal or the like, can be readily dug without interference from the piles.

While I have shown whatI consider to be a` preferred embodiment'ofmy invention, it

willof` course be understood that ksuch embodiment is merely exemplary of the essence of the invention md that .DTIOPOr-nsia'nd i the arrangement of the parts can be 'varied considerably without departing therefrom.

l/Vhat l claim as my inventionand desire to secure by Letters Patent, isf

@1. lnY pile driving apparatus, the combiv nation of a cylinder, ram and base embodied in a hammer unit, a base extension rigidly Y' secured to and depending fromsaid base, and an impacting member guided yby :said

base extension, said impacting member being adapted to rest upon the 'upper end of the `pile and to receive the driving blows'o'f the ram.

v2. ln pile driving apparatus,'rthe c'ombina-` 'y tion of a cylinder and ram embodied in a hammer unit, an impacting member disposed between said Arain and the head'of vthe pile,

and guide meansiixefdly secured to said liamy mer unit for guiding the lower end of said impacting member and the upper end ofthe aile.

an impacting member adapted to have its lower'end rest on the upper end of the pile andadapted to receive-the blows of said driving unitat its upper end, and guide means cooperating with the lower portion of said impacting member andrigidly 'securedfto said ydriving unitl for laterally restraining the lower part of ysaid impacting member and the upper end of the pile.

4.l ln pile driving apparatus, the combina'- tion ofderrickleads, a hammer runit mounted therein and comprising -a cylinder and ram for driving the pile,ia`nd a tubular guide fixedly secured as a depending 'extension lof said hammer unit for laterally guiding the upperv end of the pile after it has been driven belowground level. f

nation of a pair of kderriclr leads, a hammer unit, a follower member adapted to be interposed between said hammer unit and the upper end of the pile and to follow the end of the pile below v'ground level, and guide means receiving theg'uiding influence of said hammer unit for laterally vguiding the lower end of said followermember andthe upper end of said pile after the lowerend of said follower member has passedbeyoiid the guidi'n'giniiuence of said leads. y Y. v 6. Inpile `driving apparatus, the combination of. a cylinder, ramand basel embodied 1n a hammer unit, a guide extension iixedly secured to .and 4'depending vfrom said base, an

intermediatefmember vertie'ally guidedv byy i,

5. In pile driving apparatus, the Vcombi-` '3. In a pile driving apparatus, the combi- `nation of a pair of leads of a vderricl frame,

.driving unit reciprocating between said'leads,

- of the pile, and releasable means for, compellingsaidguide extension to Vitollow the downward movement of the pile below gi'ound level.

7. JIn a pile driving apparatus, the combination of a cylinder, ram and base embodied in a hammer unit, a vbase extension depending therefrom, a core guided for vertical movement in said base extension, the lower end of said core vbeing adapted to rest on the upper end of the pile'and the upper end of saidvcore receiving the driving blows of said ram directly, and a releasable key for coupling saidvbase extension and said core tohammer unit to the upper end of the pile,

releasable .means for compelling downward movement of said extended base with the pile below ground level, and means for indicating the penetration of the pile for each driving blow when said base extension is released from said core member. l 9. In pile driving apparatus, the combination of a cylinder, ram and base embodied in a hammer unit, a tubular extension iixedly secured to and depending from said base, a core vertically guided within said'tubular extension and delivering the driving blows of saidiram to the upper end of the pile, and means for compelling downward -movement of said tubular extension and said core below ground level, said latter means being releasable to permit said core to transmit a blow to the pile unimpeded by the resistance of said .tubular extension for measuring the load bearing value of the pile. l0. In pile driving apparatus, the combination of a cylinder, ram and base embodied in a hammer unit, a-tubular extension depending from said base, a core vertically guided within said tubular extension and transmitting the driving blows of said ram to the Aupper en'd of said pile, releasable means for compelling said tubular extension to frollowthe downward movement of the pile below ground level,and a sight opening in said tubular extension through which the movement of the core,k and thereby the movement y ets secured to said casing and engaging withsaid base to tixedly suspend said casing there-` from, and a core vertically guided lwithin said tubular extension. p

v13. ln pile driving apparatus, the combination of a cylinder, ram and base embodied in a hammer unit, a cylindrical casing, a plurality of' brackets extending between said base and saidcasing for fixedly securingsaid casing below said base, means permitting disconnection of said brackets to permit separa-V tion of said casing and base, and a `core vertically guided within said casing.

14. In pile driving apparatus, the combination otra cylinder, ram and base embodied in a hammer unit, vertically extending columns joining said cylinder and lsaid base, a tubular casing depending from said base, brackets secured to said casing and embracing the sides of said base, supporting extensions on said brackets engaging said columns, and a core vertically guided within said casing. g Y

15. In pile driving apparatus for driving composite piles having sleeve extensions on their upper ends, the combination of a cylin-V der, ram and base embodied in a hammer unit,

a Vtubular extension tixedly securedto vand depending from said base,and a ram within said tubular. extension, the lower "end of said ram being receivable within the sleeve'extension on the upper end of a composite pile for transmitting the driving blows of the ram directly to the'lower section of said pile, said tubular extension embracing and guiding said ram and said sleeve extension.

16.'.In pile driving apparatus,'the combination of a cylinder, ram'andbase embodied in a' hammer unit, a tubular extension depending from said base and connected there` to, a core extending longitudinally of said tubular extension, a collar onthev upper Vportion et said core, andan arcuate key plate in a key slot` in said tubular extension and engaging with said collar.

17. lnpile driving apparatus, the combi` nation of guide leads, a cylinder, ram and base embodied in a hammer unit and having guiding engagement with said leads, a sleeve portion fxedlysecured to said base whereby said sleeve portion receives the benefit ofthe guiding `engagement of said hammer yunit with `said leads, and a follower guided at im upper end within said sleeve portion and 12. n-pile driving apparatus, the combiiio iis

adapted to transmit the driving blows of said ram to the pile. i 1 i y 18. In pile driving yapparatuafthe combination of a Cylinder, rain and base embodied 5 in a hammer unit, a sleeve liXedlv secured to said base, a follower having relative reciproeatory movement within said sleeve, said follower transmitting the driving blows of said ram to the pile, shoulder means on said folw lower and cooperating shoulder means on said sleeve adapted to engage during the lifting of said hammer unit for lifting said follower from the upper end of the pile.

19. In pile driving apparatus, the combination of a cylinder, ram and base embodied in a hammer unit, a sleeve Xedly secured to said base and depending therefrom, and a follower guided at its upper end within said sleeve, said base having an opening therein, said ram imparting `driving blows 'to said follower through said opening, said follower transmitting said blows to the upper end of the pile.

f JOSEPH H. THORNLEY. 

